FACTORS ASSOCIATED WITH THE PATTERN OF MATERNAL WEIGHT-GAIN DURING PREGNANCY

Objective: To examine the pattern of maternal weight gain using matern al characteristics and pregnancy outcome. Methods: We used maternal we ight data measured prospectively from all deliveries between 1980-1990 at the University of California, San Francisco. Piecewise linear regr ession was used to estimate the rate of maternal weight gain in each t rimester. Bivariate techniques were used to examine associations betwe en maternal weight gain per trimester and maternal characteristics and pregnancy outcomes. We also used multiple regression analysis to exam ine the relationship between maternal characteristics and trimester we ight gain. Results: Weight data for at least one trimester were availa ble for 10,418 women. The average rate of weight gain (kg/week) was lo west during the first trimester (0.169 +/- 0.268, n = 7587), peaked du ring the second trimester (0.563 +/- 0.236, n = 8000), and slowed slig htly in the third trimester (0.518 +/- 0.234, n = 10,052). Maternal he ight, hypertension, cesarean delivery, and fetal size correlated posit ively with the rate of gain in each trimester, but pre-pregnancy body size, age, parity, smoking status, race-ethnicity, and diabetes were a ssociated differently with gain, depending on which trimester was exam ined. The most important maternal predictors of weight gain per trimes ter were age and Asian race-ethnicity in the first trimester; pre-preg nancy body mass, parity, and height in the second; and hypertension, a ge, and parity in the third. Conclusion: Maternal weight gain per trim ester is associated with a number of maternal characteristics and preg nancy outcomes, and these relationships vary according to which trimes ter is being examined.